Using various manual and automated systems and methods, whole blood is collected and separated into its clinical components (typically red blood cells, platelets, and plasma). The collected components are typically individually stored and used to treat a variety of specific conditions and diseased states.
Before transfusing the collected blood components to a recipient in need of the components, or before subjecting blood components to further treatment, it is often desirable to minimize the presence of impurities or other materials that may cause undesired side effects in the recipient. For example, because of possible reactions, it is generally considered desirable to reduce the number of leukocytes in blood components before storage, or at least before transfusion (i.e., “leukoreduction”).
Filters are widely used to accomplish leukoreduction in blood products today (e.g., filtration of leukocytes from whole blood, red cells, and/or platelet products). Filters typically include a filter media disposed between mating and/or opposed walls of a filter housing. Inlet and outlet ports associated with the housing provide flow to and from the interior of the filter. Traditionally, the walls of the filter housing have been made of a rigid, typically polymeric, material. More recently, filters wherein at least the walls of the housing are made of a flexible material have been used in blood collection kits. Soft or flexible housing filters provide the advantage of being able to withstand handling and centrifuging without breakage of the filter. Examples of soft housing filters are disclosed in U.S. Pat. No. 6,367,634; U.S. Pat. No. 6,422,397; U.S. Pat. No. 6,745,902; U.S. Pat. No. 7,353,956; U.S. Pat. No. 7,332,096; U.S. Pat. No. 7,278,541; and U.S. Patent Application Publication No. 2003/0209479, all of which are hereby incorporated by reference herein.
While flexible housing filters are now commonly used in the field of blood processing, there exists an ongoing desire to improve the construction, performance, and manufacturability of such filters.